Browse Prior Art Database

Method of Sealing Graphite Crucibles for High Temperature Application

IP.com Disclosure Number: IPCOM000095954D
Original Publication Date: 1964-Oct-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Holtzberg, F: AUTHOR [+2]

Abstract

Certain high temperature processes or chemical reactions must be carried out at constant volume, e. g., to avoid losses of a volatile component, to establish an equilibrium pressure, etc. A procedure which satisfies this condition uses crucibles of non-reactive material which can be sealed. Sealing graphite containers is difficult because of the mechanical properties of this material.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 88% of the total text.

Page 1 of 2

Method of Sealing Graphite Crucibles for High Temperature Application

Certain high temperature processes or chemical reactions must be carried out at constant volume, e. g., to avoid losses of a volatile component, to establish an equilibrium pressure, etc. A procedure which satisfies this condition uses crucibles of non-reactive material which can be sealed. Sealing graphite containers is difficult because of the mechanical properties of this material.

This method seals graphite crucibles against gas pressure reactively welding the graphite through the formation of high melting carbide using low melting metals. In the drawing, sample A is melted at a temperature of 2000 degrees C. Above 900 degrees C a volatile component starts to evaporate. In order to avoid losses of this component, a graphite container is used and sealed as shown.

The metal part of the piston-fitting plug, such as La, melts and reacts with graphite at 800 degrees C forming a high melting carbide LaC(2) having a melting point of 2355 degrees C. Such provides a weld between the graphite plugs and the container forming a solid high melting pressure tight seal. By using a thermal gradient, it is possible to initiate the welding process with minimum heating of the sample. Instead of La, other metals such as Co, Cr, Ni, Si, Ce and the other lanthanide metals can be used, which have a low melting point or form a low melting eutectic initially and which, however, form a high melting carbide as the re...